As neutrophils are the first type of leukocyte to localize to a site of infection, small synthetic peptides that bind with high affinity to cell-surface receptors that mediate chemotaxis of neutrophils provide a rational basis for the development of an infection specific radiopharmaceutical. The preliminary data indicate that this approach is viable. The investigator proposes to build on the initial work by synthesizing new Tc-99m labeled peptides with improved infection- localizing and pharmacokinetic characteristics and to evaluate them in vitro and in vivo in an animal model of infection. The best performing peptide that meets appropriate design criteria will be selected for clinical testing.